Method of masking photographic film while exposure is being made



Sept. 16 1924.

L. F. DOUGLASS mmaon OF msxme PHOTOGRAPHIC FILM WHILE sxrosum: 1s BEING MADE Filed July 15, 1922 Patented Sept. 16, 19724.

U IT D STATES 1,508,509 PATENT OFFICE.

LEON I. DQUGLASS, OF IENLO BARK, CALIFORNIA.

METHOD OF IASKJIIYG BKQTOGBAPHIC' FILI WHILE EXPOSURE IS BEING MADE.

Application filed July 15, 1922. Serial No. 575,310.

Tooll whom it may concern:

Be it known that'I, LEON F. DOUGLASS, a citizen of the United States,and a resident of Menlo Park, in'the county of San Mateo and State of'California,-have invented new and useful Improvements in the Methods of,

a convenient method for producing a plurality of separate scenes or images from separate negative films on. a single positive film.

The invention is illustrated in the accompanying drawin s in which:

Fig. 1 is an. eevation-view showing the clear glass together with an opaque member attached thereto;

Fig. 2 is a similar view of the clear glass together with another opaque member of different shape attached thereto;

Fig. 3 is a diagrammatic fragment of a photographicfilm upon which are produced two images from two separate negatives by means of the clear glass and the opaque members shown in Figs. 1 and 2;

Fig. 4 is a sectional view of a portion of a prmting machine, showing the relative arrangement of the negative and positive photographic films, the clear glass and an opaque member attached thereto.

In the drawings, A, is a rectangular piece of clear glass or a transparent celluloid which is so proportioned that it fits within a printing machine and covers one frame of the film or the entire surface of a plate. B and B are opaque members, consisting of pieces of black cloth or other suitable materials which will not permit light rays to pass through them. B and B are attached to A by means of glue or any other suitable adhesive, and are placed thereon in such a manner that the portion of the film upon which no exposure is to be made, is covered thereby. Figure 4, shows in section, a portion of a printing machine, in which the clear glass A, together with the opaque member B, are placed in printing position between the printing light L, and the ne tive film F. Behind the negative film? is placed the positive film F, upon whichthe titles. or a plurality of different sceneqor images are to be produced. When two separate scenes or images are to be produced on a positive film, the o aque members B and B. are so formed or shaped that one exactly fits within the other, as shown in Figs. 1 and 2. Thus when exposure is being made to light L in a print ng machine, a portion of the positive film F and one oft e negatives will be covered by one of the opaque members, while in making a second exposure the positive film F and the other negative will be covered in such a manner by the other of the opaque members that the portions thereof which were not exposed by the previous exposure, will be subjected to the light rays from light L. Before exposing the positive film to the light rays from light L a second time, the opaque member B Wlll be removed from clear glass A and the other opaque member B will be placed thereon in such a position, that it will cover its surface except for the part thereof previously covered by opaque member B. Thus, by the first exposure the positive film F 'isexposedto light rays from light L except for the part thereof which is covered by opaque member B, while in the second exposure, the part thereof covered by opaque member B is not exposed, and the part previously covered by B is exposed. In the first exposure one particular negative is employed so as to produceon the pos: itive film F the scene appearing thereon, while in the second exposure a different negative is employed so as to produce a different scene thereon. Thus for instance, suppose it is desired to roduce on a ositive film, a scene showing t e interior 0 a theatre in which a motion picture is being displayed. The positive film F and a ne ative, upon which appears the interior of a t eatre scene, are inserted in the proper printing position ivithin a printing machine. Opaque member B is attached to clear lass A, and placed thereon in such a positlon that the light rays from light L are not permitted to strike the" part of the positive upon which the motion picture screen is to appear. The clear glass A and the opaqge member B are inserted in the printer, tween light L and the negative F. Then by exposure, the interior of the theatre is produced on positive film F, with an unexposed portion appearing thereon which 1s to vvbe exposedon a second operation of the.

printing machine. After the first exposure, a second negative is selected, upon which ap pearsany particularimage or scene, and it,

together with the positive film F are insert ed within the printing machine, as before. The opaque member B is removed from clear glass A, and the other opaque member B is attached thereto, care being taken to placeit in a position which will'exactly cover that portion of positive film F previously exposed, and still leave an openlng covered orig nally by B. The clear glass A previously covered by B, thereby producing a scene from the negative, on the part of the positive film where the motion picture screen is to appear. Thus by two exposures and by the use of the clear glass A, together with the opaque members and B, two separate scenes are produced on' a single I positive film.

It is to be understood thatI am not limited to any particular kind of clear glass for the attachment of the opaque members, as the same satisfactory results can be ac' complished by using a transparent celluloid,

upon which can be photographed the opaque members. Therefore the term clear glass is to be construed as applying to both-transparent celludoid and glass, and opaque members is'to be construed as applying to any substance or materialwhich will not permit light rays topass through it.

It is to be expressly understood that I am not limited to: any particular kind or form of photography, as it is apparent that my invention maybe used in. connection with both still motion photography or cinematography.'

Havingdes'cribed my invention, What I'ec'laim is: u f y 1. The method of producing two separate.

images on a positive film which comprises,

attaching an opaque member of particular shape to atransparent support adapted to cover one frame'of the positivefilm, placing the opaque member and transparent support in the pathof the light rays from a printing light, making a print ifnoin a selected negative film upon thepositive film by means of the light rays passing through the transparent support and the selected negative film, removing the opaque member from the transparent support, and attaching thereto another opaquemember adapted to mask the portion of the transparent, sup

port not masked by the first mentioned opaque member, interposing the last men- 'tionedopaque member and transparent support in the path of the light rays proceeding froma printing light through another selected negative film to the positive film, and making an exposure of said positive film to the light rays passing through the transparent support and, the second selected nega tive film.) v

2. The method of producing two separate scenes on a positive film whichcomprises,

firstly masking portions of a positive film by means of an opaque member of particular shape supported by a transparent member and exposing the unmasked portions of the positive filmto the light rays passing through the transparent member and a selected negative film, and secondly, masking the portions of the positive film previously exposed, by means of an opaque member of another particular shape supported by the transparent member, and exposing the pos1 tive film to the light rays passing through the transparent memberand a second selected negative film; v 3. Themethod of producing ,twoseparate images on' apositive film which comprises inserting an opaque member of vparticular shape supported by a transparentmember within .a. printing machine, exposing the positive ,to'the light rays proceeding through thetransparent support and a selected negative film, substituting for the first entioned opaque member another opaque member-adaptedto cover the portion of the transparentsupportnot covered by the first opaque member, inserting the transparent support and the opaque member within the prlnting machine, and exposing the portions of the positive film not previously exposed to the lighti rays proceeding through the transparent support and a second selected 

